Conditional sentences are useful because they help us talk about facts, habits, rules, possibilities and future results. In this lesson, you will practise two common types of conditional sentences: the zero conditional and the first conditional.
The main difference is simple:
- We use the zero conditional to talk about facts or things that are generally true.
- We use the first conditional to talk about possible future situations and their probable results.
Zero Conditional: Facts and General Truths
We use the zero conditional when we talk about facts, rules, habits or things that usually happen in the same way.
The structure is:
If + present simple, present simple
Examples:
If you heat water to 100°C, it boils.
If people don’t sleep well, they feel tired.
If plants don’t get water, they die.
In these sentences, we are not talking about one specific future situation. We are talking about facts or general truths.
You can also practise the present simple before working with conditional sentences.
Now complete the exercise below with the correct form of the verb.
First Conditional: Possible Future Situations
We use the first conditional when we talk about possible future situations and their probable results.
The structure is:
If + present simple, will + verb
Examples:
If it rains tomorrow, we will stay at home.
If you study tonight, you will pass the test.
If she feels better, she will come to class.
In these sentences, we are talking about possible situations in the future. The result is also possible or probable.
Now complete the exercise below with the correct form of the verb.
Zero vs First Conditional: What Is the Difference?
The zero conditional and the first conditional are similar because both use if + present simple in the first part of the sentence.
The difference is in the result:
Zero conditional:
We use the present simple in both parts of the sentence because we are talking about facts or general truths.
If you heat ice, it melts.
First conditional:
We use will + verb in the result because we are talking about a possible future situation.
If it rains tomorrow, we will stay at home.
Compare these examples:
If you heat water, it boils.
This is a general fact.
If it rains tomorrow, we will stay at home.
This is a possible future situation.
Now complete the final exercise and choose the correct form of the verb.
Final Tip
A good way to remember the difference is this:
Use the zero conditional for facts, rules and things that are generally true.
Use the first conditional for possible future situations and their probable results.
Keep practising with short examples. The more you compare both structures, the easier it becomes to choose the correct one.
For a more detailed explanation of English conditionals, you can also check the Cambridge Dictionary guide to conditionals with if.
